October 7 is Niels Bohr’s birthday. Bohr was a Danish physicist best known for his research into atomic structure and quantum theory.
Bohr developed a model of the atom where the positively charged nucleus was surrounded by electrons orbiting in discrete energy levels. The chemistry of the atom would then be determined by the number of electrons contained in the outermost energy levels. This theory also explained the visible spectra given off by elements. Bohr’s model showed the transition of an electron from a higher energy level to a lower energy level would release a photon of light equal to the difference in energy between the two levels. When applied to the hydrogen atom, the predicted energy levels corresponded to the spectral lines observed from hydrogen. This verification of his model would earn him the 1922 Nobel Prize in Physics.
Bohr also attempted to explain the structure of the atom’s nucleus. His theory was known as the “liquid drop model”. This model had the nucleons of the atom’s nucleus behaving like the molecules in a drop of liquid. If enough energy is pumped into the nucleus, the liquid nucleus will deform and split into smaller fragments and release energy in the process. This theory contributed to the understanding of what was happening when uranium atoms were observed to split into smaller pieces when neutrons were introduced.
Bohr spent much of World War II in Denmark continuing his research. He also helped German refugees escape from the Nazi Party. Shortly after being notified of his own arrest by the occupying German forces, Bohr left Denmark to Sweden and then to England. While there, he was recruited into the Tube Alloys program, Britain’s version of the Manhattan Project. His involvement with this project did not hinder his desire for the peaceful applications of atomic energy. He was part of the group that developed CERN and their laboratories.
Bohr’s laboratory was responsible for many of the early contributions to quantum mechanics. The Institute for Theoretical Physics in Copenhagen where he did much of his work was renamed the Niels Bohr Institute in his honor. Element 107, Bohrium was named in his honor.
Notable Science Events for October 7
2008 – George Emil Palade died.
Palade was a Romanian cytologist who shares the 1974 Nobel Prize in Medicine with Albert Claude and Christian de Duve for their discoveries in cell function and organization. The discovered the vacuole that is present in all plant cells and some animal and bacteria cells. The vacuole are enclosed compartments in the cell membrane that contain enzymes in solution that maintain cell health and conditions.
1994 – Niels Kaj Jerne died.
Jerne was a Danish immunologist who shares the 1984 Nobel Prize in Medicine with Georges Köhler and César Milstein for their work concerning the immune system and discovery of monoclonal antibodies. He developed theories as to how the body produces the many different antibodies to protect the body from infection, the thymus is used to distinguish between its own components and those that are foreign and the immune system can self-regulate to turn itself on or off as needed.
1959 – First view of the far side of the Moon photographed.
The Soviet space probe, Luna 3 successfully took the first photographs of the far side of the Moon and relayed them back to Earth.
The photographs of the previously unseen part of the Moon was vastly different from the front side. The photographs showed mountainous terrain with only two dark ‘sea’ regions named Mare Moscovrae (Sea of Moscow) and Mare Desiderii (Sea of Desire).
1939 – Harvey Cushing died.
Crushing was an American neurosurgeon who was the pioneer of modern neurosurgery. He was the first to use x-rays to locate brain tumors, introduced the sphygmomanometer to measure blood pressure to the United States, and discovered Cushing’s disease. This disease is caused by a malfunction of the pituitary gland.
1939 – Harold Walter Kroto was born.
Kroto is an English chemist who shares the 1996 Nobel Prize in Chemistry with Richard E. Smalley and Robert F. Curl, Jr. for the discovery of fullerenes. Fullerenes are a group of carbon allotropes that form spheres, tubes or planes. The spherical fullerene, C60, is called a buckyball or buckminster fullerene. The tubes are called bucky tubes or carbon nanotubes. The planes are called graphene.
1885 – Niels Bohr was born.
1835 – François Magendie died.
Magendie was a French physician and physiologist who pioneered the field of experimental physiology. He proved and elaborated Charles Bell’s observation that the anerior roots of spinal nerves are motor in function, where the posterior roots communicate sensory impulses. He also studied the effects of many drugs on different parts of the body and introduced the use of morphine and strychnine in medical practices.
1822 – Rudolf Leuckart was born.
Leuckart was a German zoologist who was a pioneer in parasitology. He researched tapeworms and trichinosis.
He also discovered the tapeworm Taenia saginata only infects cattle and Taenia solium only infects pigs.